Arrangement of a high vacuum electronic discharge tube provided with a getter ion pump operating in magnetic fields

ABSTRACT

AN ION PUMP FOR OPERATION WITH A HIGH VACUUM ELECTRONIC DISCHARGE TUBE IS PHYSICALLY LOCATED WITHIN EXTERNAL COLUMNS OF PERMANENT MAGNETIC DISCS PRODUCING THE MAGNETIC FIELD REQUIRED FOR OPERATION OF THE TUBE. THE ION PUMP USES PART OF THIS MAGNETIC FIELD FOR ITS OWN OPERATION.

United States Patent Inventor Appl. No.

Filed Patented Assignee Priority Wolfgang Schmidt Hamburg, Germany 800,643

Feb. 19, 1969 June 28, 1971 U.S. Philips Corporation New York, N.Y.

Feb. 28, 1968 Germany ARRANGEMENT OF A HIGH VACUUM ELECTRONIC DISCHARGE TUBE PROVIDED WITH A GETTER ION PUMP OPERATING IN MAGNETIC FIELDS 3 Claims, 4 Drawing Figs.

U.S. Cl

[51} Int.C1 H0lj7/l6, H01j25/5O [50] FieldofSearch 3l3/7,7.5, 7.3.63, 153, 154, 160, 161, 323; 315/535, 39.71; 230/69 [56] References Cited UNITED STATES PATENTS 3,173,048 3/1965 Chun 313/7 3,278.85? 10/1966 Peters..... 3l3/7X 3,368,100 2/19168 Detro 313/7X Primary Examiner-John Kominski Assistant ExaminerE. R. LaRoche AttorneyFrank R. Trifari ABSTRACT: An ion pump for operation with a high vacuum electronic discharge tube is physically located within external columns of permanent magnetic discs producing the magnetic field required for operation of the tube. The ion pump uses part of this magnetic field for its own operation.

PATENTEUJUHZSIQYI 3588.563

INVENTOR.

WOLFGANG SCHMIDT afl AGEN ARRANGEMENT OF A HIGH VACUUM ELECTRONIC DISCHARGE TUBE PROVIDED WITH A GET'I'ER ION PUMP OPERATING IN MAGNETIC FIELDS The invention relates to a high vacuum electronic discharge tube operating in a magnetic field generated by columns of permanent magnets outside the tube, which tube is provided with a getter ion pump operating also in a magnetic field.

Getter ion pumps are connected to high vacuum discharge tubes to keep the gas pressure within the tube as low as possible. Microwave discharge tubes have comparatively heavy metal parts, from which under the influence of the discharge, occluded gas is set free. This gas not only may poison the cathode or disintegrate it, but the ions may also influence the working of the tube by their oscillations, which among others contribute to noise. In beam tubes the ions may give rise to such a contraction of the electron beam, that the collector electrode locally melts and evaporates.

The problem for the tube manufacturer is however how to combine the tube and the getter ion pump and their magnetic fields.

From the German patent application laid open to public inspection under N0. l,248,8l9 it is known to arrange the getter ion pump in the stray field of the magnetic system of a microwave magnetron. The magnetic field of the magnetron has such a high intensity that the stray field is sufficiently intense (l,000 to L500 Gauss) for the operation of a getter ion pump.

From the French Pat. No. 1,329,758 it is known to arrange a multicavity power klystron in the field of an electromagnet in which also the getter ion pump is arranged.

Klystrons with magnetic fields generated by columns of permanent magnets as shown in FIG. 4 of the German Pat. No. l,l5 8,1 83 operate with a rather low intensity of the magnetic field. Due to this the stray field is not sufficient for the accommodation of a getter ion pump. Also when such magnets are used for magnetron tubes requiring a less intense magnetic field the intensity of the stray field is not sufl'icient for a getter ion pump.

The invention aims at a solution for this problem.

In the arrangement of a high vacuum electronic discharge tube operating in a magnetic field generated by columns of permanent magnets outside the tube, which tube is provided with a getter ion pump also operating in a magnetic field, the getter ion pump is arranged in one of the columns of permanent magnets, such that at least part of the flux lines of the main magnetic field of the tube house the getter ion pump.

Due to the arrangement according to the invention the intensity of the magnetic field in the getter ion pump will obtain a higher value than if it were arranged in the stray field.

To compensate of the asymmetry, which follows from the presence of the pump in one of the columns of permanent magnets, the other columns may be provided with an intermediate part of about the same dimensions as the pump soft magnetic or nonmagnetic. Also it is possible to arrange two or more pumps in a symmetrical arrangement in the other columns of permanent magnets. The invention is now described more fully by reference to the drawing, in which FIG. I is a view of one section of a power klystron partly cut away from which section FIG. 2 is a top view.

FIG. 3 is a side view of a magnetron according to the invention and FIG. 4 a top view.

In FIGS. 1 and 2 I designates drift tubes of a klystron defining an interaction gap 2. Ceramic tubes 3 with copper flanges 4 define the vacuum chamber. Cavity resonators may be attached to flanges 4. Pole plates 5 connect columns 7 of permanent magnet discs 6. Pole plates 5 bear pole shoes 8. In FIG. I the left column 7 has in the middle thereof a soft magnetic disc 9. In the right column 7 instead of the disc 9 a getter ion pump I0 is arranged connected by the pump lead 11 to the drift tubes I. On both sides of the pump lead 11, cooling fins 2 are arranged. If desired a second pump can be provided for reason of symmetry in another column.

FIGS. 3 and 4 iffer from FIGS. I and 2 in that only two columns 7 are provided. The pole plates 5 bear poles l7 arranged in the anode body l5. I3 is the cathode insulator and 14 the cathode lead. l6 denotes the output lead.

lclaim:

I. A high vacuum electronic discharge tube comprising an envelope containing electrodes for producing and controlling electron beams, columns of permanent magnetic discs external to said envelope to produce a magnetic field for interaction with said beams and an ion pump connected to said envelope to reduce gas pressure within said envelope, said ion pump being arranged within one of said columns whereby at least part of the flux lines of said magnetic field passes through said ion pump.

2. A high vacuum electronic discharge tube as claimed in claim I, further comprising an intermediate part of desired magnetic characteristics having substantially the same dimension as said ion pump arranged within one of the other columns to compensate for any asymmetry caused by said ion pump.

3. A high vacuum electronic discharge tube as claimed in claim I, further comprising ion pumps arranged within two or more symmetrical columns.

9 2 23 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,5 3,5 3 Dated June 28. 1971 Invencorys) WQLFGANCL SCHMTD'I It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 2, line 8, the sentence that begins with The invention should start a new paragraph.

line 24, after arranged" insert -on the drift tube 1. Figure 2 shows how four columns 7 are arranged.

Signed and sealed this 2nd day of November 1971.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GO'I'TSCHALK Attesting Officer Acting Commissioner of Patents 

